Young Avocado Tree - brown "rust" spots

I'm located in San Diego, and we've grown a hass avocado from a pit. The tree is about a year old. It's in a large pot, outside on our east-facing patio. Recently it started getting brown rust-like spots on many of the leaves. It also has some holes in the leaves. Today we found the cuprit for the holes - a green caterpillar. But we still need to figure out what is causing the brown spots. Here are some photos. Please advise. Thank you so much!

Avocados are not my area of expertise. Hope you don't mind me taking a stab at it.

Looks like a leaf spot fungus on the upper leaves. Maybe a very advanced stage of the leaf spot on the dead lower leaves. When watering keep the water off the foliage, I see the wet leaves in the pics. These trees are very sensitive to being over fertilized & water with high salts. Also they need lots of sun through the day not just in the morning.

We found mealybugs on the tree several weeks back. Does this look like damage they could do? Based on other photos I've seen online, we thought it perhaps might be spider mites or brown mites. Thoughts?

“We found mealybugs on the tree several weeks back. Does this look like damage they could do? Based on other photos I've seen online, we thought it perhaps might be spider mites or brown mites. Thoughts?

No, looks fungal with the spots on the upper leaves.

The lower leaves have a interveinal issue going on. See how the leaf veins are green & the other areas are not. This is a possible symptom of poor soil/water issues, sun scorch, wind burn etc. or as I stated before an advanced stage of the leaf spot fungus.